By David S. Lawyer. mailto:davylawyer1@gmail.com
November 2007, Jan., Mar. 2008
INTRODUCTION
When old galvanized pipes in your home build up rust and calcium
deposits inside, water flows slow. One solution is to replace the
pipes with copper (copper repiping). There are also strong
chemicals that have been tried. A third way, an alternative to
copper repiping, is to physically remove the rust and calcium (pipe
deposits) by using an electric drill to rod out (drill out) the
deposits. How to do this is as follows:
MAKING UP THE DRILL BIT
I did this for my home and the water now flows almost twice as fast
(in gallons per minute). Here's how I did it. I first made a long
drill bit about 22 ft. long by buying a 3/4 inch drill bit with a
1/2" shank and also buying a 21 ft. length of 3/8 inch galvanized
steel pipe. Using a hammer and a block of wood so as not to damage
the tip of the bit, I drove the drill bit shank into the pipe. The
result is a 21+ ft. long drill bit suitable for drilling out scale
from a long 3/4" straight galvanized water pipe.
PUTTING THE DRILL BIT IN THE CHUCK
Now I put this long bit into a 3/8 " electric drill. To do this,
use a 3/8" to 1/8" reducer coupling and a short piece of 1/8" pipe
a couple inches long. The 1/8" pipe (OD is about 3/8") fits nicely
into the electric drill chuck, but it's best to file 3 flats on the
1/8" pipe so that it will not slip in the chuck during high
torque.
FLUSHING OUT THE DEBRIS
So then with this 22 ft. bit, start drilling out the scale inside
your old 3/4" galvanized pipes. It's a good idea to provide flowing
water for both lubrication and removal of sediment when drilling. I
used a faucet which was on the sprinkler system and thus didn't get
shut off when I shut off water to the house. Using a hose and a
special hose coupling I fed water thru the 3/4" pipe in a direction
opposite to which I was drilling. This continuously washed out the
deposit fragments busted up by the drill. But make sure you don't
drill into the hose. For example, use a short length of clean pipe
with one end connected to the end of the hose and the other end
coupled to the end of the pipe you're cleaning. When the drilling
gets too easy, you're at the end of the clogged pipe.
DRILLING TECHNIQUE
Don't let the drill stall. If it is about to stall, back off some
(pull it back) so that it'll speed up and then go forward again. Of
course a 1/2" electric drill would have been better but I didn't
have one. Also, for pipes you've removed for drilling out, you
obviously need to use a pipe wrench or vice to keep them from
rotating when you drill them out.
GETTING ACCESS
Luckily, I have enough unions under the house so I can remove all
of the 3/4" pipes that need removing so I can run the drill bit
thru them. Elbows and tees can be cleaned out with a short drill
bit and a screwdriver. Removing some exterior faucets allowed
drilling from the outside without removing pipes. If you don't have
enough unions to be able to remove pipe that needs to be removed,
you could install unions. To do this, saw the pipes, rent a pipe
threader, and install unions. A long straight run of 40 ft. could
be drilled out (without removing) by drilling from each side.
HALF INCH PIPES
For 1/2" branch lines I used a 1/2" snake made for sewer lines. The
1/2" pipes were not as badly clogged as the 3/4" pipes so this
worked OK. None of the 1/2" pipes needed to be removed and were
rodded out in place.
FLUSHING THE LINES
Then, after the job is done, turn on faucets to flush out the
system. You may need to also open angle stop valves, since clogs of
sediment may form behind them. In my case, I had to pound one with
a hammer to free a clog. But even after flushing, the water may
appear a little rusty. Flushing certain lines after a week or so
helped. If it's only iron oxide (rust) and calcium, drinking this
stuff shouldn't hurt you, but we drink purified water stored in
glass jugs so it didn't affect us.
HOW LONG DOES IT TAKE
The rate of drill feed is at least a few feet per minute with a
3/8" electric drill so most of the working time is spent removing
and reinstalling those pipe sections that need removing.
BURIED PIPES
Buried pipe would be hard to do. But some buried pipes for watering
landscape may not be too clogged up unless they've been heavily
used. The long drill bit is somewhat flexible and might work on
buried pipes if you dug a long, gently sloping, trench down to the
buried pipe. But it may be better to use chemicals or to just dig
up the buried pipe and replace it with a larger diameter pipe (say
1 1/4 inch galvanized) so that it it will take a very long time for
it to clog up. Replacing it with copper is another possibility but
then corrosion may form at the galvanized-to-copper union, even if
it is insulated so as not to pass electric current. Such an
insulating union might also impair the grounding of your house's
electric power supply if it is grounded using water pipes.
AMOUNT OF SCALE BUILD UP
You will find that the amount of scale build up is roughly
proportional to the amount of water that has flowed thru the pipe
over the past years. So the heaviest scale build up is in the line
where the water from the meter enters the house.
POUNDING ON PIPES
They used extra strong 1/2" galvanized pipe to supply one of our
bathrooms. This pipe is also extra small in inside diameter and
thus clogs up easily. I removed some scale from it by pounding on
it with a hammer while the water was flowing. My wife observed the
rusty appearance of the water flowing out the faucet so she could
tell me when further pounding was futile.